EXPLAIN EXTENDED

From Stack Overflow:

Hello,

I want to write a SELECT statement as follows:

SELECT  field_a
FROM    my_table
WHERE   field_b IN (my_function(field_c))

Is that possible?

Would my_function have to return an array?

It is of course possible in PostgreSQL using a set returning function.

Return type of such a function should be declared as SETOF, so the function will return a rowset of given type.

There are at least two ways to call this function, and in this article I will consider the benefits and drawbacks of each method.

Let's create sample tables:
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